A basic photovoltaic system comprises a photovoltaic generator such as a solar panel, which may be connected to a load. Since the power output from a photovoltaic generator varies with operating conditions, for instance the time of day, it is normal to include a battery in the system such that the load can be powered asynchronously with the photovoltaic power generation.
In order, inter alia, to derive the maximum power from the photovoltaic generator across a range of operating conditions, including the variation in insolation due to for instance cloud cover or the solar inclination, conventional photovoltaic systems include a charge controller or battery charger, in line between the photovoltaic generator and the battery.
Typical high efficiency battery chargers are able detect and track the operating voltage of the photovoltaic generator at which it can produce maximum power. This operating voltage is termed the Max Power Point voltage (Vmp), and at this voltage the panel is at its maximum power point (MPP) producing maximum power (Pmax).
However, battery chargers themselves typically are not 100% efficient, and consume some power, in order to operate. The power consumed by the battery charger is thus not available to charge the battery (since it is a self powered system).
In order to improve the photovoltaic system overall, it is desirable to reduce such power consumption.